The invention relates to the drying of materials within a closed system. More particularly, the invention relates to the removal of residual solvents after cleaning with pressurized solvent.
Granular sorbent (i.e., absorbent and/or adsorbent) materials include, for example, clay, cellulose, fullers, and diatomaceous earth in compositions which have been processed, i.e., dried or sintered and crushed to the proper size. These granular sorbents are commonly used in garages, industrial facilities and other areas to absorb products such as oil, gasoline and other contaminants that have leaked or spilled. In a typical application of granular sorbent material, after the spill of a product occurs, the granular sorbent material is sprinkled over the spill and the user waits for a short period of time to allow the granular sorbent material to absorb the contaminating product.
After the granular sorbent material has been allowed to absorb the contaminant, the granular sorbent material with the contaminant is swept into a pile and put into a barrel or other receptacle for storage. Thereafter, the facility, which uses the granular sorbent material, would have prior arrangements with a used granular sorbent material disposal service. This disposal service picks up the used granular sorbent material and treats it or disposes of it in a number of ways.
Sorbent mats and pads also are used to absorb contaminants in commercial or industrial sites. The sorbent mats and pads can be cotton, polypropylene, polyethylene, or other fabrics. These sorbent mats and pads are used similarly to granular sorbent materials. After the sorbent mat or pad has absorbed the spilled products, it can be placed in a barrel or other receptacle for storage.
Three primary methods have been used for disposing of used granular sorbent material. A first disposal method is incineration. This method presents environmental problems such as potentially harmful air emissions and the necessity to landfill processed residuals, i.e., ash.
A second common practice for disposing of soiled granular sorbent material is to bury the used material in landfills. This is obviously an undesirable approach because there is the potential for the contamination of groundwater, soil, etc. when burying petroleum-based or other products.
A third alternative method of cleaning granular sorbent material involves exposing the granular sorbent material to genetically altered microbes that consume a contaminant. The purchasing, storage and use of microbes generally are not economically feasible for small shops. In addition, there is the problem of disposing of the used microbes, and equipment used to store the microbes can often be expensive.
Disposal services generally treat sorbent mats and pads by contaminant removal at a laundry service, by incineration, or by landfilling the material. Incineration and landfilling approaches are similar for mats and pads as for granular sorbent materials. The problem associated with contaminant removal with a laundry service is that many of the contaminants are flushed into the sewer system and end up at waste water treatment plants.